# Internal angle of a regular polygon

To remember the formula for the internal angle of a regular (each side is equal) polygon, you should always work out the first three polygons, i.e triangle, square and pentagon.

Therefore, the sum of all the internal angles

`=((Number of sides -2)times180)/(Number of sides)`

which is often shown as

`=((n-2)times180)/(n)`

where n is the number of sides.